Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F14/18—Monomers containing fluorine
  • C08F14/22—Vinylidene fluoride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S526/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S526/909—Polymerization characterized by particle size of product

Definitions

• This invention relates generally to the production of vinylidene fluoride polymers and more particularly to a new method for producing vinylidene fluoride polymers in the form of fine powder by suspension polymerisation in water and solvent disperse systems (or dispersions).
• a polymerisation regulator such as carbon tetrachloride or chloroform.
• the polymerisation catalyst itself, acts as a polymerisation regulator, and it is possible to regulate the degree of polymerisation by suitably varying the quantity of this catalyst.
• a vinylidene fluoride polymer obtained by polymerisation in which a substance such as carbon tetrachloride or chloroform has been used, or a catalyst has been used in a large amount has poor thermal stability and becomes coloured when melted.
• An ultimate object of the invention is to provide an economical process for producing vinylidene fluoride polymers having controllably variable properties highly suitable for uses of the polymers in various coating and lining operations such as spray coating, dispersion coating, and fluid lining.
• a watersoluble solvent selected from methanol, ethanol, dioxane, and mixtures thereof with respect to 100 parts by weight of Water
• the vinylidene fluoride radical has a very strong hydrogen-pulling action, and most organic solvents, having strong action as chain transfer agents, consequently are not suitable as solvents for producing high polymers of vinylidene fluoride.
• suspension polymerisation with only water as a dispersion medium ordinarily produces polymers of excessively large particle size of the order of from 100 to 300 microns, which cannot form good fluid layers and are unsuitable for use in powder coating.
• the polymers produced in accordance with the present invention have particle sizes freely selectable in the range of from 1 to 200 microns. While these polymers can, of course, be formed into ordinary shaped articles and structures, including films, they are particularly suitable for coating and covering purposes such as spray coating, fluid lining, and dispersion coating (i.e., coating with a polymer dispersed in a solvent).
• methanol methyl alcohol
• ethanol ethyl alcohol
• dioxane ethyl alcohol
• methanol and ethanol are preferable since they have the desirable characteristics of little chain transfer action and the eifect of lowering the surface tension of the dispersion medium.
• radical-generating catalysts such as peroxycarbonates
• a particularly suitable catalyst is a diakylperoxydicarbonate representable by the general formula 0 noi ioor ion (where R is a radical selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobuty, sec-butyl, and t-butyl radicals).
• R is a radical selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobuty, sec-butyl, and t-butyl radicals.
• This catalyst is used in a quantity of from 0.01 to percent by weight, preferably from 0.1 to 1.0 percent by weight, relative to the vinylidene fluoride monomer.
• the polymerization can be carried out at a polymerisation temperature of from -50 to +50 degrees C., the most suitable range is from to 30 degrees C. for obtaining good results with respect to the polymer particle state and polymerisation speed.
• suspending agent substances such as polyvinyl alcohols, celluloses, gelatines, and carboXymethyl-celluloses can be used, but the use of a polyvinyl alcohol or a cellulose in a quantity of from 0.1 to 1.0 percent relative to the monomer is preferable. While the polymerisation can be carried out with a (monomer/water) ratio of /2 or less, a (monomer/ water) ratio of from /2 to /3 is preferable from the viewpoint of productivity.
• the ratio with respect to the solvent can be freely varied depending on the magnitude of the chain transfer action of the solvent, the degree of polymerisation (expressed in terms of inherent viscosity of the polymer desired, and the desired particle size of the polymer.
• the solvent concentration is excessively high, the degree of polymerisation of the resulting vinylidene fluoride polymer will be excessively low, and a polymer for forming a strong film cannot be produced.
• from 200 to 0.1 parts by weight of the solvent relative to 100 parts by weight of water is used.
• an even more preferable concentration range is from 1 to 200 parts by weight in the case of methanol and from 0.5 to 100 parts by weight in the case of ethanol with respect to 100 parts by weight of water.
• aldehydes are present. Since aldehydes greatly impair the poylmerisation of vinylidene fluoride, it is necessary to ensure that the alcohol to be used does not contain aldehydes.
• Preferable polymer particle sizes are below 40 microns for spray coating and dispersion coating and from 100 to 150 microns for fluid lining. While polymers having intrinsic viscosities (an indication of the degree of polymerisation, measured on the basis of 0.4 g./10O cc. DMF, at 30 degrees C.) of from 0.2 to 2.0 can be easily prepared, we have found that polymers having m of from 0.8 to 1.30 produce the most satisfactory results in coating.
• the apparent or bulk density of the polymer is a very 4 important property for the above mentioned applications and is preferably over 50 g./d1. However, this value also can be radily varied to suit the application by further adding the monomer during the polymerisation process.
• the present invention provides a method by which, in comparison with known methods, vinylidene fluoride polymer powders of highly desirable properties can be produced with simple and low-cost process steps.
• Example 1 2,600 grams (g.) of water, 720 g. of methanol, 10.8 g. of methylcellulose, 12 g. of diisophopylperoxydicarbonate uses as a polymerisation catalyst, and 2.4 g. of sodium pyrophosphate (Na P O .10H O) are charged into a 6-litre stainless-steel autoclave (of an inner diameter of 130 mm. and a depth of 470 mm.), which is then thoroughly evacuated. Then, as the autoclave is maintained at a temperature below 20 degrees C. in a constant-temperature water bath, 1,200 g. of vinylidene fluoride monomer is conducted through a pipe from a monomer cylinder placed on a Weighing balance to the autoclave and is thereby transferred and caused to condense within the autoclave.
• sodium pyrophosphate Na P O .10H O
• the monomer cylinder is slightly heated since, otherwise, the temperature of the cylinder would drop because of the loss of the latent heat of vapourisation of the monomer, and the transfer of the monomer would thereby stop.
• the temperature of the constant-temperature bath is raised to 25 degrees C., and polymerisation of the batch thus charged is carried out at an agitation speed of 800 r.p.m.
• the polymerisation pressure is initially 40 kg./cm. but begins to decrease after approximately 12 hours because of the reaction progress, dropping to 20 kg./cm. in 27 hours after the start of polymerisation.
• the polymerisation is stopped at this point, and after the still unreacted monomer has been discharged, the resulting polymer is filtered, washed with water, and then dried for 20 hours at a temperature of from 70 to degrees C.
• Example 1 An autoclave as specified in Example 1 is charged with 2,600 g. of water, 720 g. of methanol, 10.8 g. of methylcellulose, 12 g. of diisopropylperoxydicarbonate used as a polymerisation catalyst, and 2.4 g. of sodium pyrophosphate (N21 P O -10H O) and is then thoroughly evacuated. Then the autoclave is charged with 1.2 kg. of vinylidene fluoride monomer in the same manner as set forth in Example 1.
• Polymerisation is then carried out according to the procedure as set forth in Example 1 except that, when the polymerisation pressure, which is initially 40 kg./ cm. reaches a value of from 30 to 35 kg./cm. as the reaction progresses, 360 g. of the monomer is added anew in the same manner as described above.
• the polymerization pressure thereupon returns to 40 kg./cm. but again drops to from 30 to 35 kg./cm. after 10 hours.
• a second supplementary addition (400 g.) of the monomer is thereupon carried out.
• the polymerisation pressure becomes 20 kg./cm. whereupon the reaction is stopped, and the resulting polymer is filtered, washed with water, and dried at from 70 to 80 degrees C. for 20 hours.
• Example 3 An autoclave as specified in Example 1 is charged with 2,650 g. of water, 350 g. of ethyl alcohol, 9 g. of methylcellulose, and 10 g. of diethylperoxydicarbonate and then with 1,000 g. of vinylidene fluoride monomer in the same manner as set forth in Example 1. Polymerisation of the charge is then started at 25 degrees C with agitation at 800 r.p.m. When the polymerisation pressure reaches 25 kg./cm. a supplementary addition of 350 g. of the monomer is carried out, and a second supplementary addition of 300 g. of the monomer is carried out at a pressure of 35 kg./cm
• 1,320 g. (80-percent yield) of a polymer was thus obtained.
• This polymer had a particle size in the range of from 5 to 50 microns, an apparent density of 56 g./dl., and an intrinsic viscosity m of 0.55 and was found to be suitable for use in spray coating and dispersion coating.
• Example 4 An autoclave as specified in Example 1 is charged with 3,3 80 g. of water, 120 g. of dioxane, 3.6 g. of methylcellulose, 12 g. of diisopropylperoxydicarbonate, and 2.4 g. of Na P O -10H O and then with 1,200 g. of vinylidene fluoride monomer, and the polymerisation process is started in the same manner as set forth in Example 1.
• the pressure within the autoclave is at 20 kg./ cm. at which time a further 400 g. of the monomer is added to the batch, and then, when the pressure has again dropped to 20 kg./cm. the reaction is stopped, and the resulting polymer is processed in the same manner as set forth in Example 1.
• a polymer was thus obtained with a yield of 88 percent.
• This polymer had a particle size in the range of from 20 to microns, an apparent density of 52 g./dl., and an intrinsic viscosity 1 of 0.70 and was found to be highly suitable as a polymer for fluid lining.
• polyvinylidene fluoride by suspension polymerization in the presence of a peroxydicarbonate compound as polymerization catalyst and a suspending agent
• the improvement which comprises adding 0.1 to 200 parts by weight of a water-soluble solvent selected from the group consisting of methanol, ethanol, dioxane, and mixtures thereof per 100 parts by weight of water, as an agent for regulating the degree of polymerization and particle size of the resulting polymer product, and carrying out the suspension polymerization reaction at a temperature of from 10 to 30 0., thereby obtaining polyvinylidene fluoride having fine particle sizes of from 1 to microns in diameter.
• a water-soluble solvent selected from the group consisting of methanol, ethanol, dioxane, and mixtures thereof per 100 parts by weight of water

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerisation Methods In General (AREA)
• Paints Or Removers (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=12118746

Family Applications (1)

Country Status (4)

Cited By (4)

Family Cites Families (1)

• 1968
  • 1968-04-04 US US718924A patent/US3574178A/en not_active Expired - Lifetime
  • 1968-04-11 FR FR1560112D patent/FR1560112A/fr not_active Expired
  • 1968-04-13 DE DE1770199A patent/DE1770199C2/de not_active Expired
  • 1968-04-16 GB GB07999/68A patent/GB1175654A/en not_active Expired

Also Published As

Similar Documents